Emergence of a multiple-input multiple-output (MIMO) technology brings a revolutionary change to wireless communication. A plurality of antennas are simultaneously deployed on a transmit end device and a receive end device, so that the MIMO technology can simultaneously provide a plurality of mutually independent channels, and therefore, a data transmission rate is multiplied. Precoding is used in the MIMO technology. In a conventional one-level precoding structure, a quantity of radio frequency channels is the same as a quantity of transmit antennas.
In massive MIMO, a large quantity of antennas are used to improve link quality, cell coverage, system performance, and spectrum efficiency. To obtain a high spatial degree of freedom that can be provided by large-scale antennas, a data transmit end needs to obtain related channel state information (CSI), so as to implement accurate precoding.
When there are a small quantity of antennas on the data transmit end, pilot overheads and a CSI feedback amount can be controlled. However, when there are a relatively large quantity of antennas, pilot overheads and a CSI feedback amount occupy a large quantity of time-frequency resources, and consequently time-frequency resources available for data transmission are compressed, and a system throughput is severely affected.